1,849,991 research outputs found
Breast support garments are ineffective at reducing breast motion during an aqua aerobics jumping exercise
The buoyant forces of water during aquatic exercise may provide a form of ‘natural’ breast support and help to minimise breast motion and alleviate exercise induced breast pain. Six larger-breasted females performed standing vertical land and water-based jumps, whilst wearing three breast support conditions. Underwater video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated as well as exercised induced breast pain scores. Key results showed that the swimsuit and sports bra were able to significantly reduce the superioinferior breast range of motion by 0.04 and 0.05 m, respectively, and peak velocity by 0.23 and 0.33 m/s, respectively, during land-based jumping when compared to the bare-breasted condition, but were ineffective at reducing breast kinematics during water-based jumping. Furthermore, the magnitude of the swimsuit superioinferior breast range of motion during water-based jumping was significantly greater than land-based jumping (0.13 m and 0.06 m), yet there were no significant differences in exercise induced breast pain, thus contradicting previously published relationships between these parameters on land. Furthermore, the addition of an external breast support garment was able to reduce breast kinematics on land but not in water, suggesting the swimsuit and sports bras were ineffective and improvements in swimwear breast support garments may help to reduce excessive breast motion during aqua aerobic jumping exercises
Some properties of the range of super-Brownian motion
We consider a super-Brownian motion . Its canonical measures can be
studied through the path-valued process called the Brownian snake. We obtain
the limiting behavior of the volume of the -neighborhood for the
range of the Brownian snake, and as a consequence we derive the analogous
result for the range of super-Brownian motion and for the support of the
integrated super-Brownian excursion. Then we prove the support of is
capacity-equivalent to in , , and the range of , as
well as the support of the integrated super-Brownian excursion are
capacity-equivalent to in ,
Reliable camera motion estimation from compressed MPEG videos using machine learning approach
As an important feature in characterizing video content, camera motion has been widely applied in various multimedia and computer vision applications. A novel method for fast and reliable estimation of camera motion from MPEG videos is proposed, using support vector machine for estimation in a regression model trained on a synthesized sequence. Experiments conducted on real sequences show that the proposed method yields much improved results in estimating camera motions while the difficulty in selecting valid macroblocks and motion vectors is skipped
Motion of influential players can support cooperation in Prisoner's Dilemma
We study a spatial Prisoner's dilemma game with two types (A and B) of
players located on a square lattice. Players following either cooperator or
defector strategies play Prisoner's Dilemma games with their 24 nearest
neighbors. The players are allowed to adopt one of their neighbor's strategy
with a probability dependent on the payoff difference and type of the given
neighbor. Players A and B have different efficiency in the transfer of their
own strategy therefore the strategy adoption probability is reduced by a
multiplicative factor (w < 1) from the players of type B. We report that the
motion of the influential payers (type A) can improve remarkably the
maintenance of cooperation even for their low densities.Comment: 7 pages, 7 figure
Motion Analysis Strategy Appropriate for 3D Kinematic Assessment of Children and Adults with Osteogenesis Imperfecta
Human motion analysis provides a quantitative means of assessing whole body and segmental motion of subjects with musculoskeletal pathologies. This chapter describes a low cost motion analysis appropriate for complete three-dimensional (3D) assessment of upper and lower extremity kinematics. The system has been designed to support lower cost outreach efforts that require accuracy and resolution on the order of classical fixed lot systems such as Vicon. The focus of this work addresses the assessment needs typically seen in adults and children with osteogenesis imperfect (OI) experiencing ambulatory and upper extremity challenges
Axisymmetric bending oscillations of stellar disks
Self-gravitating stellar disks with random motion support both exponentially
growing and, in some cases, purely oscillatory axisymmetric bending modes,
unlike their cold disk counterparts. A razor-thin disk with even a very small
degree of random motion in the plane is both unstable and possesses a discrete
spectrum of neutral modes, irrespective of the sharpness of the edge. Random
motion normal to the disk plane has a stabilizing effect but at the same time
allows bending waves to couple to the internal vibrations of the particles,
which causes the formerly neutral modes to decay through Landau damping.
Focusing first on instabilities, I here determine the degree of random motion
normal to the plane needed to suppress global, axisymmetric, bending
instabilities in a family of self-gravitating disks. As found previously,
bending instabilities are suppressed only when the thickness exceeds that
expected from a na\"\i ve local criterion when the degree of pressure support
within the disk plane is comparable to, or exceeds, the support from rotation.
A modest disk thickness is adequate for the bending stability of most disk
galaxies, except perhaps near their centers.
The discretization of the neutral spectrum in a zero-thickness disk is due to
the existence of a turning point for bending waves in a warm disk, which is
absent when the disk is cold. When the disk is given a finite thickness, the
discrete neutral modes generally become strongly damped through wave-particle
interactions. It is surprising therefore that I find some simulations of warm,
stable disks can support (quasi-)neutral, large-scale, bending modes that decay
very slowly, if at all.Comment: 19 pages plain TeX with 7 PostScript figures; tarred, gzipped and
uuencoded (406 KB). Revised version submitted to Ap
Topological Mixing with Ghost Rods
Topological chaos relies on the periodic motion of obstacles in a
two-dimensional flow in order to form nontrivial braids. This motion generates
exponential stretching of material lines, and hence efficient mixing. Boyland
et al. [P. L. Boyland, H. Aref, and M. A. Stremler, J. Fluid Mech. 403, 277
(2000)] have studied a specific periodic motion of rods that exhibits
topological chaos in a viscous fluid. We show that it is possible to extend
their work to cases where the motion of the stirring rods is topologically
trivial by considering the dynamics of special periodic points that we call
ghost rods, because they play a similar role to stirring rods. The ghost rods
framework provides a new technique for quantifying chaos and gives insight into
the mechanisms that produce chaos and mixing. Numerical simulations for Stokes
flow support our results.Comment: 13 pages, 11 figures. RevTeX4 format. (Final version
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